The fixed entry node is a new feature called entry guards aimed at preventing locating Tor hidden servers.

Just to explain for the OP. Gov agencies with great power can jam up the TOR network in a way where many normal entry servers are busy and conveniently their servers are available for you to connect to. Then they do the same thing on the exit node server. If a 3 letter agency gains control of your entry AND your exit relay SIMULTANEOUSLY they can completely unmask you in short order. Many/some advanced users edit their torrc files to only permit entry servers they KNOW. This is a debatable practice but in either regard it prevents traffic capture available to an "agency" with control of entry and exit nodes. Your TOR bundle doesn't limit you to ONE entry forever, but it does prevent random cycling through tons of relays, where you could be captured as described above.

It is all a matter of who you trust more. Do you trust a random alphabet soup agency with an interest in depriving you of your privacy "for your protection"? Or would you trust your own choice of entry nodes more? I doubt many here would pick the former, and that is a good thing. Choose wisely.

Debugging is at least twice as hard as writing the program in the first place.

So if you write your code as clever as you can possibly make it, then by definition you are not smart enough to debug it.